Color photography



Patented July 2a, 1938 UNITED STATES PATENT OFFICE COLOR PHOTOGRAPHY No Drawing. Application July '7, 1936, Serial No. 89,458. In Germany July 13, 1935 6 Claims.

Our present invention relates to color photography and more particularly to developing in colors.

One of its objects is an improved process of developing in colors. Another object is a new developer for developing in colors. Further objects will be seen from the detailed specification following hereafter.

This invention is based on the observation that 10 iso-oxazolones and their substitution products may be used with advantage for color development. They are, in particular, superior to other substances proposed and known for the purpose owing to their free solubility, including solubility 5 in solutions alkaline with sodium carbonate; with the developers generally applied in color development, for instance, a paraphenylene diamin'e, they yield pictures which are red to blue according to the substituent in the iso-oxazolone. They are particularly interesting because they easily give the blue-red tint necessary for color photography, which has not hitherto been easily-produced. They have the further advantage that the dyestufis produced from them are stable to Farmers reducer, which is used for removing the silver picture produced by development. The

' iso-oxazolone may not only be added to the developer but may also be incorporated in the silver halide emulsion layer.

The iso-oxazolones are. made from acylacetic acid esters and hydroxylamine in alkaline solution. azolone named in Example 2 may be made by mixing 1 mol. of terephthaloyl-acetic acid ester with 2 mols of hydroxylamine hydrochloride and 3 mols of caustic soda, in 2 liters of water, and

- allowing the mixture to stand at ordinary temperature and then precipitating the required body by means of acetic acid.

The material'i's added to the developer in concentration suitable for obtaining the desired intensity of color in the picture.

The following examples are prescriptions of suitable developers:

Example 1.-A developer consisting of 8 grams of diethyl-para-phenylenediamine 6 grams of phenyliso-oxazolone 20 grams of anhydrous sodium carbonate 100 cc. of acetone 900 cc. of water For example, the phenylene-bis-iso-oxyields on addition to the silver picture a violet dyestuiT-picture.

Example 2.A developer consisting of 5 grams of dimethyl-para-phenylenediamine-sulfate 10 grams of phenylene-bis-iso-oxazolone 12 grams of anhydrous sodium carbonate 1000 cc. of water yields, after removal of the developed silver, a red-violet picture.

- What we claim is:

1. The process of developing an exposed silver halide emulsion in color which comprises treating, in the presence of an iso-oxazolone, said exposed emulsion with an aromatic amino developer the oxidation product of which forms a colored compound with said iso-oxazolone.

2. The process of developing an exposed silver halide emulsion in color which comprises treating, in the presence of a phenyl-iso-oxazolone, said exposed emulsion with an aromatic amino developer the oxidation product of which forms a colored compoundwith said phenyl-iso-oxazolone.

3. The process of developing an exposed silver halide emulsion in color which comprises treating, in the presence of a phenylene-bis-iso-oxazolone, said exposed emulsion with an aromatic amino developer the oxidation product of which forms a colored compound with said phenylenebis-iso-oxazolone.

4. A developer for the production of colored pictures comprising an iso-oxazolone and an aromatic amino developer, the oxidation product of which forms a colored compound with said iso-oxazolone.

5. A developer for the production of colored pictures comprising a phenyl-iso-oxazolone and an aromatic amino developer the oxidation product of which forms a colored compound with said phenyl-iso-oxazolone.

6. A developer for the production of colored pictures comprising phenylene-bis-iso-oxazolone and an aromatic amino developer the oxidation product of which forms a colored compound with said phenylene-bis-iso-oxazolone.

JOHN EGG-ERT. BRUNO WENDT. 

